Lab Notes: This Is Your Brain on Ecstasy

A common drug-of-abuse shrinks the brain's memory manager, and a common pre-IVF screening test for genetic abnormalities may be faulty. These and other recent research tidbits are covered this week in Lab Notes.

Ecstacy Takes Away Memory

If people take drugs to help them forget their problems, ecstacy users may be doing so most effectively.

The drug -- technically known as 3,4-methylenedioxymethamphetamine, or MDMA -- may actually shrink the hippocampus, which plays a central role in memory, according to a study in the Journal of Neurology, Neurosurgery, and Psychiatry.

Among 10 patients who popped an average of 280 pills over the past 6.5 years, MRI scans revealed that their hippocampal volume was reduced about 10.5% compared with seven other drug users whose preferences ran in other directions.

The study authors said theirs is the first to show the drug's effect on structural changes in the brain. Prior work has established that ecstacy users tend only to be deficient in memory, with scores on other cognitive tests usually normal.

-- K.F.

Doubt Cast on Polar-Body Testing in IVF

A test often used to screen for genetic abnormalities during in vitro fertilization procedures may give false results, according to a study in the American Journal of Human Genetics.

One method of identifying such abnormalities is to examine mitochondrial DNA (mtDNA) in the polar body, a semi-autonomous structure within the oocyte that disappears after fertilization. It's long been assumed that this DNA is identical to that which the mother would contribute to her offspring.

But a study by researchers at several French labs and Vanderbilt University in Nashville indicates that, in fact, the "mutant load" in mtDNA extracted from polar bodies can differ substantially from that in oocytes and blastomeres, the actual reproductive cells.

The r2 coefficient of correlation between mutational frequencies in mtDNA in polar bodies versus the other cell types was only 0.52, well short of perfect, the researchers found.

"Individual discrepancies in mutant loads between polar bodies and their counterparts make polar body-based preconception diagnosis unreliable for the prevention of mtDNA disorder transmission," they wrote.

-- J.G.

Soy as Radiosensitizer

A cocktail of three isoflavones found in soy may impair the ability of lung cancer cells to withstand the effects of radiation, while helping to protect normal cells, researchers found.

Researchers led by Gilda Hillman, PhD, of Wayne State University in Detroit, treated human A549 non-small cell lung cancer cells with three soy isoflavones -- genistein, daidzein, and glycitein -- and compared the cells with others that were not treated. They then exposed all of the cells to radiation.

The cells that were treated with isoflavones showed greater damage from the radiation, included DNA double-strand breaks. There was also an increase in gamma-H2AX foci, indicating increased DNA damage and an inhibition of repair mechanisms.

"These natural soy isoflavones can sensitize cancer cells to the effects of radiotherapy by inhibiting the survival mechanisms that cancer cells activate to protect themselves," Hillman said in a statement. "At the same time, soy isoflavones can also act as antioxidants, which protect normal tissues against unintended damage from the radiotherapy."

The results were reported in the Journal of Thoracic Oncology.

-- T.N.

Folk Medicine May Deserve Testing in RA

A plant alkaloid present in traditional Chinese herbal medicines may have potential as a nontoxic therapy for rheumatoid arthritis, if clinical studies confirm laboratory and animal findings.

Weidong Zhang, PhD, from the Second Military Medical University in Shanghai, and colleagues tested the alkaloid, berberine, on antigen-presenting dendritic cells in vitro. The compound is believed to have antibiotic and antiinflammatory properties.

After determining that berberine induced apoptosis in these cells, the researchers then tested it on mice with collagen-induced arthritis. Both humoral and cell-mediated immune responses were suppressed, preventing the infiltration of inflammatory cells into the synovium and the resulting damage to cartilage and bone.

These findings suggest that further studies are warranted to investigate a potential therapeutic role for berberine in rheumatoid arthritis, the researchers wrote in the April issue of Arthritis & Rheumatism.

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